Field of the Invention
The invention relates to the testing of large areas. Thereby, particularly tests with a corpuscular beam are used as a testing method. In particular, the present invention relates to the contacting of test objects. Specifically, the present invention relates to a method for positioning and contacting a substrate, a method for the testing of a substrate, and an apparatus for contacting at least one test object for the test and to a test system.
With increasing demand on display elements without picture tubes, the standards for liquid crystal displays (LCD) and other display elements, in which control elements, for example thin film transistors (TFT), are used increase. These display elements have pixels arranged in a matrix.
Yet, also in other fields an increasing amount of elements has to be tested. This can be, for example, microelectronic and/or micromechanic elements. These elements are for example thin film transistors, connection networks of a chip, transistors, electron emitters of an emitter array, the electrodes for pixels of a display, micromechanic mirrors of an array and other elements, which distinguish themselves in particular by being present as a plurality of elements (100,000 a to several 1,000,000), whereby each element is electrically controllable.
In order to obtain, for example, a good image quality of a display element, only a few of the several million pixels are allowed to be defective. For guaranteeing a cost efficient production it is therefore important, most notably for the display elements continuously increasing in size, to provide high-capacity in situ test methods. Such a test method is for example disclosed in document EP 523594. Within this test method, the individual pixels are tested with a corpuscular beam. The corpuscular beam can either be used for detecting charges applied via a supply line and/or applying charges on a pixel electrode.
For such test methods contact units are employed, which, on the one hand, allow for a signal transfer to external devices and, on the other hand, admit a scanning with an electron beam. Thereby, according to the state of the art, different solutions exist.
If displays are tested, it is possible to arrange a frame around the area of the display which provides electrical contacts to the display. On one substrate there are generally several displays arranged. Because in view of the limited measurement range of an electron beam system only one display each can be tested, for the test of a further display that contact units is lifted, the substrate is displaced and the contact unit is set on the next display. However, using such an arrangement, only displays can be tested whose entire surface can be reached by the scanning of the corpuscular beam.
Further, there are contact frames that contact all displays of a glass substrate at the same time. Such a contact frame is displaced with a substrate, if other displays are to be tested.
A disadvantage of such contact frames for the entire substrate is the necessity to exchange the entire contact frame in the event of varying display sizes. For this reason the system must be vented in the case of varying batches, which reduces the productivity. Further, it is necessary to store the contact frames for the varying display types and display sizes in order to be applied when demanded.
The object of the invention is to at least partly solve the problems of the state of the art. Particularly, the possibility should be given to test during a test different test objects with different dimensions of test objects with one apparatus.
Thereby, test objects in the context of the present invention are for example displays, a group of displays, arrays of other microelectronic or micromechanic elements, as well as individual circuits, which are for example tested on short-circuits and missing contacts between areas of the circuit.